Local and global climate change increases the ambient temperature of cities by several degrees with important consequences on energy consumption, health and the economy. Advanced urban mitigation technologies contribute to decrease the ambient temperature and counterbalance the impact of urban heat islands. The present paper analyses and presents in a comparative way the mitigation potential of the known mitigation technologies using performance data from about 220 real scale urban rehabilitation projects. The average and peak temperature drop of reflective technologies, greenery, evaporative systems, earth to air heat exchangers and their combinations is calculated and presented. The mitigation potential of the main systems like cool roofs, cool pavements, green roofs, urban trees, pools and ponds, sprinklers, fountains, and evaporative towers, is analysed. It is found that the potential of the main mitigation technologies is considerable and can counterbalance UHI effects partly or fully. The average peak temperature drop calculated for all projects is close to 2 K, while the corresponding decrease of the average ambient temperature is close to 0.74 K. Almost 31% of the analysed projects resulted in a peak temperature drop below 1 K, 62% below 2 K, 82% below 3 K and 90% below 4 K.
Highlights:

The average peak temperature drop from mitigation techniques is close to 2 K.

The decrease of the average ambient temperature is close to 0.74 K.

Almost 31% of the projects resulted in a peak temperature drop below 1 K and 62% below 2 K

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Cool roof technology is known to reduce the cooling energy consumption of conditioned buildings during hot periods, and widespread implementation of such roofs in a neighbourhood or precinct can mitigate the urban heat island effect.

Cities are vulnerable to temperatures, and the task of cooling them has proved challenging.
The CRCLCL is developing a decision-support tool that bridges the gap between research and practical application in urban microclimates by helping governments, developers and planners to mitigate vulnerability to urban heat island effects.

The implementation of ‘cool’ roofing materials, with high solar reflectance and infrared emittance, has received significant attention in recent years, as a method to mitigate the urban heat island effect and reduce building cooling energy requirements. The effect of ‘cool’ roofs on heat transfer through the roof structure has been investigated by many researchers.